Arabis serotina is a rare species of flowering plant in the mustard family

Brassicaceae

Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....

 known by the common name shale barren rockcress. It is native to eastern West Virginia

West Virginia

West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

 and western Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

 in and around the Shenandoah Valley

Shenandoah Valley

The Shenandoah Valley is both a geographic valley and cultural region of western Virginia and West Virginia in the United States. The valley is bounded to the east by the Blue Ridge Mountains, to the west by the eastern front of the Ridge-and-Valley Appalachians , to the north by the Potomac River...

, where it is known from fewer than 60 populations. It is endemic to the shale barrens, a type of habitat characterized by steep slopes of bare shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

, an exposed, rocky habitat type that is subject to very dry and hot conditions. Shale barrens host a number of endemics, such as Allium oxyphilum and Taenidia montana, and this rockcress is among the rarest. It is a federally listed endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

.

Characteristics

This is a biennial herb which has a small, inconspicuous basal rosette of leaves measuring just a few centimeters wide. It bolts with an erect, branching stem that can reach a maximum height near one meter. Leaves along the stem may be 5 to 15 centimeters long, lance-shaped, and sometimes toothed along the edges. Leaves wither early, and the plant may have few or no leaves at flowering. The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 is a raceme

Raceme

A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...

 of several tiny white flowers each under a centimeter wide. The fruit is a silique

Silique

A silique or siliqua is a fruit of 2 fused carpels with the length being more than three times the width. The outer walls of the ovary usually separate when ripe, leaving a persistent partition...

 measuring 4 to 8 centimeters in length and containing many small seeds.

Habitat

This endangered plant grows in mid-Appalachian

Appalachian Mountains

The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...

 shale barrens, an eroding shale scree

Scree

Scree, also called talus, is a term given to an accumulation of broken rock fragments at the base of crags, mountain cliffs, or valley shoulders. Landforms associated with these materials are sometimes called scree slopes or talus piles...

 of Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 origin. This habitat occurs in Virginia Pine woodlands and is made up of unstable rock and thin soils which are largely weathered fragments of shale known as channery. Most populations of the plant have just a few individuals. The rocky soils receive direct sunlight that makes them too hot (up to 63°C) to support many plant species.

Endangered status

The plant was listed as a federally endangered species in 1989. In Virginia, it was given an S1 ranking ("Critically Imperiled") in 1991.

The plant is pollinated

Pollination

Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...

 by the Grizzled Skipper (Pyrgus wyandot), a species of butterfly which is declining in numbers. Its decline in some areas has been attributed to the use of the pesticide

Pesticide

Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

 Dimilin to control gypsy moth

Gypsy moth

The gypsy moth, Lymantria dispar, is a moth in the family Lymantriidae of Eurasian origin. Originally ranging from Europe to Asia, it was introduced to North America in the late 1860s and has been expanding its range ever since...

 (Limantria dispar). Other threats to the species are loss of shale barren habitat to the construction of railroads, hiking trails

Hiking

Hiking is an outdoor activity which consists of walking in natural environments, often in mountainous or other scenic terrain. People often hike on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking...

, and a dam

Dam

A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

. Many populations are heavily browsed by deer

Deer

Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

. It is not a successful competitor against introduced species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 such as barren brome

Bromus sterilis

-Introduction:Bromus sterilis is an annual or biennial species of bromegrass known as barren brome, poverty brome, and sterile brome.-Range:...

 (Bromus sterilis) and tree of heaven (Ailanthus altissima).